Cell Structure & Function — Part 7: 7 MCQs with Explanations

Passive natural immunity provides temporary protection to fetus/newborn; antibodies degrade over months and no memory cells are produced.

C4 plants fix CO₂ into oxaloacetate (via PEP carboxylase) in mesophyll cells; C4 acids transported to bundle sheath cells where CO₂ released for Calvin cycle.

Megakaryocytes fragment to release 2000-3000 platelets each into bloodstream; platelets lack nuclei and survive 7-10 days.

Sister chromatids separate during anaphase of mitosis and anaphase II of meiosis; homologous chromosomes separate during anaphase I of meiosis.

Retroviruses (e.g., HIV) carry reverse transcriptase enzyme that converts their RNA genome into DNA after entering host cell; DNA integrates into host genome.

Granulosa cells of developing ovarian follicles secrete estrogen during follicular phase; corpus luteum secretes both estrogen and progesterone after ovulation.

Osmosis is passive diffusion of water across selectively permeable membrane from region of higher water potential to lower water potential.